Early diagnosis and response assessment in chronic recurrent multifocal osteomyelitis: changes in lesion volume and signal intensity assessed by whole-body MRI

Objective: To assess the effectiveness of whole-body MRI (WB-MRI) in early diagnosis of chronic recurrent multifocal osteomyelitis (CRMO) and the prediction of clinical response through quantitative MRI features. Methods: 20 children (mean age, 10.3 years; range, 5–14 years) with CRMO underwent WB-MRI and were assessed with a clinical score (Jansson) at baseline (median time after first encounter, 8 months) and follow-up (median time after baseline, 11.5 months). Baseline WB-MRI scans were classified as early (within 6 months after first encounter) and late. Clinical responders and non-responders were compared regarding number and localization of bone lesions, lesion volume and T2 signal intensity (SI) ratio (lesion to muscle). Results: Diagnosis of CRMO was made promptly in the early WB-MRI group (n = 10; median, 3 months) compared to the late WB-MRI group (n = 10; 18 months; p = 0.006). Bone lesions were mainly located in the lower extremities (n = 119/223; 53%). No significant difference was detected regarding the number of bone lesions and lesion volume in the subgroups of clinical responders (n = 10) and non-responders (n = 10). Responders showed a higher volume reduction of bone lesions at follow-up compared to non-responders (p = 0.03). Baseline and follow-up SI ratios were lower in responders (5.6 and 5.8 vs 6.1 and 7.2; p = 0.047 and p = 0.005). Conclusion: The use of WB-MRI within 6 months of disease suspicion may serve as a benchmark to support early diagnosis of CRMO. T2 SI ratios and the reduction of lesions’ volume correlate with clinical outcome. Advances in knowledge: WB-MRI at an early stage of suspected CRMO plays a key role for early diagnosis. This is the first study showing that quantitative MRI features are suitable for response assessment and can be used as prognostic markers for the prediction of clinical response.

Reply to Cantarelli et al. Chronic Recurrent Multifocal Osteomyelitis Associated with Crohn Disease: A Potential Role of Exclusion Diet? Comment on “Starz et al. The Modification of the Gut Microbiota via Selected Specific Diets in Patients with Crohn’s Disease. Nutrients 2021, 13, 2125”

We congratulate Erika Cantarelli and colleagues for the presented case report in the comment entitled “Chronic Recurrent Multifocal Osteomyelitis associated to Crohn Disease (CD): a potential role of exclusion diet [...]

Chronic Recurrent Multifocal Osteomyelitis Associated with Crohn Disease: A Potential Role of Exclusion Diet? Comment on Starz et al. The Modification of the Gut Microbiota via Selected Specific Diets in Patients with Crohn’s Disease. Nutrients 2021, 13, 2125

The efficacy of diet and its influence on gut microbiome composition has been largely demonstrated in inflammatory bowel disease (IBD). Little is known about its potential in the management of extraintestinal manifestations. We report a successful application of Crohn disease exclusion diet (CDED) in association with infliximab and methotrexate, as salvage therapy in a child affected by chronic recurrent multifocal osteomyelitis (CRMO) and Crohn disease (CD) resistant to optimized therapy. Both intestinal and bone symptoms remitted after the application of CDED. Diet may have acted on common microbic inciting agents that trigger both intestinal and bone inflammation, supporting the role of microbiota in the pathogenesis of IBD-associated extraintestinal manifestations. Our experience suggests the potential benefit of CDED in association with combined therapy in resistant patients affected by CD and extraintestinal manifestations.

P085 Chronic recurrent multifocal osteomyelitis: about 2 cases

Background Chronic recurrent multifocal osteomyelitis (CRMO) also known as aseptic osteomyelitis is a rare auto-inflammatory disease with an incidence estimated at 4/100 000 population [1]. The aim of our work was to report two cases of CRMO that illustrate challenges in the diagnosis of this rare disease. Method We report the case of two patients diagnosed with CRMO. Clinical, biological and radiological data as well as disease outcomes were described. We also collected data about treatment modalities. Results Two patients aged of 7 and 10 years respectively, without any notable pathological history, presented recurrent episodes multifocal painful swelling of limbs. In the first case, the symptoms concerned the left ankle and knee as well as the left hip, all associated with lameness and an altered general condition, with neither fever nor skin manifestations. In the second case, the swelling involved the right shoulder, right hip and the left ankle. There was no elevated CRP or ESR in any of patients. Immunological status (RF, anti-CCP, AAN) as well as the HLA-B27 antigen test were negative. In the first patient, standard radiographs showed lytic lesions of the proximal metaphysis of the tibia, the greater trochanter and the left lateral malleolus. MRI of the pelvis, knee, and sternum of the first patient revealed edematous involvement of the left greater trochanter, the right ilium, the proximal metaphyseal region of the tibia and the right edge of the sternum, whereas in the second patient, a whole-body MRI showed inflammatory signs over the left greater trochanter, the insertion of the gluteus medius and obturator externus, right trochanteric bursitis and oedema of the entire right ilium. In the first patient, bone scintigraphy showed intense uptake of radioisotopes in the left ilium, the 7 th right costo-vertebral junction, the trochanteric mass, the upper end of the tibia and the lower end of the left fibula. Bone biopsy showed bone remodeling in both cases without evidence of infection or tumor. The diagnosis of CRMO was retained, supported by the prompt response to NSAIDs and short-term corticosteroid therapy. However, the second patient presented, 8 years later, pain in the sterno-clavicular joint as well as the right hip. A relapse of the disease was confirmed by MRI. Therapeutic escalation with zoledronic acid 0.025 mg/kg intravenous infusion every six months allowed the resolution of the symptoms. Conclusion These observations illustrated a rare disorder in children, characterized by lytic lesions predominantly in the metaphysis of long bones. Bone scintigraphy allowed an early assessment of disease extension and histological examination ruled out a malignant tumor and an infection. The first-line treatment is anti-inflammatory drugs. In case of failure, bisphosphonates seem to be effective.

O007. Register of hereditary auto-inflammatory diseases in a pediatric rheumatology unit

Background Autoinflammatory diseases (AID) are a group of genetic syndromes resulting from an excessive activation of the innate immune system, caused by mutations in genes regulating the inflammatory pathways and can involve several organs. The aim of this study is to evaluate the clinical, paraclinical, epidemiogical and genetic data of Moroccan patients with confirmed AID, in order to allow a first experience of AID registry in our unit. Material We have retrospectively analyzed 30 cases of patients in our unit over a period of 13 years (between 2006 and 2019), according to inclusion criterias (recurrent fever > 3 episodes and a CRP > 40mg/L) and having excluded immune deficiency, autoimmune disease, neoplasia and infectious diseases. Results The mean age of our patients at 1st consultation was 6.9 years (with extremes ranging from 8 months to 14 years). Consanguinity was reported in 16 cases, and unknown in one case of an adopted child. The patients were classified as follows: 66% of cases with Familial Mediterranean Fever (FMF) including 1 case with a characteristic phenotype of Marshall/Periodic Fever Aphtous Pharyngitis Adenitis (PFAPA) syndrome, 16% of cases with Mevalonate Kinase Deficiency (MKD), 10% of cases with Chronic Recurrent Multifocal Osteomyelitis (CRMO), 1 patient with Familial Pustular Psoriasis (FPP) and another symptomatic patient with Muckle Wells syndrome. An association with Henoch Schonlein purpura was reported in 30% of cases and with periarteritis nodosa in 1 case in FMF patients. The mean diagnostic delay was 3 years (with extremes ranging from 1 month to 12 years). The main clinical features found in our patients included fever (83%), abdominal pain (90%), arthralgia (83%), arthritis (46%), adenopathies (40%), aphtous (30%) and other specific signs. Genetic analysis revealed that M694V was the most frequent mutation (60%), followed by A744S (15%), E148Q (10%), K695R (10%) and P369S/ R408Q (5%) in all FMF patients, and V337I found in 1 patient with MKD while the 4 others were confirmed basing on a high rate of urinary mevalonic acid. CRMO patients were confirmed by radiological and histological analysis. The case of FPP was confirmed histologically by skin biopsy and the patients with Muckle Wells and PFAPA syndroms were diagnosed basing on characteristic clinical features. Therapeutically, all FMF patients were treated with colchicine in addition of corticosteroids in 1 case of PFAPA syndrome. Patients with MKD received targeted therapy (Anakinra, Etanercept) and Ibuprofen in 1 case. CRMO patients were treated with targeted therapy and NSAIDs. The case of FPP was treated with Methotrexate combined with Etanercept and the patient with Muckel Wells Syndrome received corticosteroid therapy combined with Azathioprine and then Anakinra. The clinical and biological evolution was considered favorable in 76% of cases, partial in 13% of cases and 3 death cases were reported. Conclusion AIDs remain rare genetic syndromes whose lack of knowledge explains the late diagnostic delay. Therefore, it is necessary for any pediatrician to know how to evoke an AID in front of recurrent fever with free intervals, clinical features and inflammatory syndrome, in order to choose the optimal treatment as well as to make the genetic counseling. Abbreviations AID: Auto-Inflammatory Disease CAPS: Cryopyrin Associated Periodic Syndromes CARD14: Caspase Recruitment Domain Family Member 14 CIAS1: Cold-Induced Autoinflammatory Syndrome 1 CRMO: Chronic Recurrent Multifocal Osteomyelitis CRP: C-Reactive Protein CT scan: Computerized Tomography scan DNA: DeoxyriboNucleic Acid ESR: Erythrocyte Sedimentation Rate FMF: Familial Mediterranean Fever FPP: Familial Pustular Psoriasis IL-1β: Interleukine-1beta IL-17A: Interleukine 17A MEFV: Mediterranean fever gene MKD: Mevalonate Kinase Deficiency MVK: Mevalonate Kinase MW: Muckle Wells NALP3: NAcht Leucine-rich repeat Protein 3 NLRP3: NOD-like receptor family, pyrin domain containing 3 NSAID: Non-Steroidal Anti Inflammatory Drugs PFAPA: Periodic Fever Aphtous Pharyngitis Adenitis PRINTO: Pediatric Rheumatology INternational Trials Organization SAA: Serum Amyloid A TRAPS: TNF Receptor Associated Periodic Syndroms TNF: Tumor Necrosis Factor